Copolymerization is a versatile strategy for compositional control over structure property relationships. However, the scope of copolymerization typically encompasses strictly mechanistically compatible monomer classes such as pure (metha)crylate, or epoxide systems. There are many reports of the heterocopolymerization of disparate classes of monomers such as epoxides and carbon dioxide, and/or cyclic anhydrides, and examples of copolymerization between epoxides and lactones have been reported for lactones incapable of homopolymerization; copolymerization of carbon dioxide and butadiene has also been reported recently (Sudo, A. et al.; Zhang, Y.; Endo, T. Anionic Alternating Copolymerization of Epoxide and Six-Membered Lactone Bearing Naphthyl Moiety. J. Polym. Sci. A Polym. Chem. 2010, 49, 619-624; Tadokoro, A. et al. Anionic Ring-Opening Alternating Copolymerization of a Bicyclic Bis(Gamma-Lactone) with an Epoxide: a Novel Ring-Opening Polymerization of a Monomer Containing a Gamma-Lactone Structure. Macromolecules 1993, 26, 4400-4406; Nakano, R. et al. Copolymerization of Carbon Dioxide and Butadiene via a Lactone Intermediate. Nature Chemistry 2014, 6, 325-331).
Multicomponent polymerizations of an array of monomer species have also been reported, with the specificity of a zinc-based catalyst resulting in block copolymers formed from feed mixtures encompassing epoxide, lactone, anhydride, and carbon dioxide comonomers (Romain, C. et al. Chemoselective Polymerizations From Mixtures of Epoxide, Lactone, Anhydride, and Carbon Dioxide. J. Am. Chem. Soc. 2016, jacs.5b13070). Romain et al. reported that ε-caprolactone and cyclohexene oxide could be statistically copolymerized into block copolymers, but that heterosequences between the two monomers did not occur spontaneously. What is needed is a general synthetic strategy that would enable the direct copolymerization of epoxides and lactones that are both capable of homopropagation to high molecular weight. The compounds, compositions, and methods disclosed herein address these and other needs.